The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
Aspects of the invention relate to a winding mechanism for a sunscreen, for use in an open roof construction for a vehicle.
In prior art sunscreens having a winding mechanism (also known as rollo sunscreens) the spring member, mostly a metal helical torsion spring, is covered by a sleeve preventing the spring member from touching the winding tube. Also it is possible that a winding shaft is mounted inside the hollow shape of the helical torsion spring and whereby a sleeve is used around the shaft to prevent the spring from touching the outer surface of the shaft such as been disclosed in EP 2 610 093. When no sleeves are used the spring member will rattle or scrape against the inner surface of the winding tube or the outer surface of the winding shaft resulting in an unpleasant noise for the passengers of the vehicle. Such noises can occur when the winding mechanism is operated but also when the vehicle makes certain dynamic movements. Due to the torque applied between the spring member ends and the rotational movement of a part of the spring and also due to the dynamic movements applied to the winding mechanisms the spring temporarily engages with the sleeves. These engagements are often accompanied by impacts and forces which the spring member applies to the sleeves. This causes the sleeve to be moved from its original position exposing a part of the winding tube or winding shaft which may cause rattle. Sleeves may be secured in their proper position with the help of a tape, however these connections often are not reliable during the lifetime of the winding mechanism.
Furthermore the problem occurs with the prior art sleeves that when the helical spring member is tensioned (wound) and, due to this, has a decreased diameter, and at the same time the shape of the spring member has a tendency to be deformed from a more or less straight cylindrical shape into a helical shape extending along its length, whereby thus the spring member may engage the sleeves. Such engagements may cause a rotational movement of a local part of the sleeves, especially when the sleeves are not firmly fixed to the spring member or the winding shaft. These rotational movements of part of the sleeves induce that the sleeves wrinkle and obstruct the spring member in its function. For instance the spring member may cause higher roll out forces of the sunscreen or the winding mechanism is not capable to wind the sunscreen onto the winding tube.